Cut the chicken breasts in cubes, but don't make them too small. 3cm is fine.
Sear in a pan with vegetable oil and a few drops of sesame oil for that extra asian taste. Just put enough cubes so that the pan is covered with some space in between them. This way you know they will become golden. Add salt and pepper.
Once the chicken is done, add the pepper and cook it a bit with more oil. Add salt and pepper.
Make the lettuce wraps and enjoy!